Thermostat-actuated alarm



' (No Model.)

11-13. BIGELOW. THERMOSTAT AGTUATED' ALARM.

No. 555,069. I Patented Feb. 25, 1896.

A TTOHNE).

UNITED STATES FRANK B. BIGELOIV,

PATENT OFFICE.-

OF AUBURN, MAINE.

TH ERMOSTAT-ACTUATED ALARM.

SPECIFICATION forming part of Letters Patent No. 555,069, dated February25, 1896.

Application filed September 6, 1895. Serial No. 561,674. (No model.)

To aZZ whom, it may concern.-

Be it known that I, FRANK B. BIGELOVV, a citizen of the United States,residing at Auburn, in the county of Androscoggin and State of Maine,have invented certain new and useful Improvements in Thermostat-ActuatedAlarms, of which the following is a specification.

My invention relates primarily to alarms which are used in connectionwith dentists vulcanizers, but is useful for other purposes. It belongsto that class of thermostatic devices in which a compound metallic baris placed in contact with the walls of a heated chamber, is acted uponby the heat transmitted through these walls, and is adjusted to indicatea certain definite temperature of the interior of the chamber. An alarmof this general character is the subject of application Serial No.498,268, filed January 27, 1894, by F. B. Bigelow and V. P. Buck.

. The object of my invention is to provide a device which shall beapplicable to dentists vulcanizers of all styles and shapes, shall beeasy to adjust accurately, and little liable to derangement.

In the accompanying drawings, Figure l is a side elevation of themachine; Fig. 2, an end elevation.

In the drawings, A is the compound metallic bar which serves at the sametime as the supporting-framework of the device and its actuatingthermostat.

The bar A is made'u p of a relatively-thick inside strip, 17, of brass,and an outer relatively-thin strip, 0, of steel, which is united withthe brass by soldering and riveting. At one end the brass strip 1)extends beyond the steel and is bent inward to support the alarm D,which, as shown, is an ordinary clock-alarm released by the detent d,which presses against the wedge-shaped part 10 of the releasing-rod R.This rod passes through the brass strip 1), and its T-shaped head II ispressed against the grooved back of the strip Z) by the spring "1). Theother end of R is notched and rests upon the adjusting-screw S, which isturned by the thumb-piece h. The rotating stop t,which surrounds theshank of the adjusting-screw and has a projection against which thethumb-piece h strikes, is

Figs. 3 and 4 show details.-

held in place by the two clamping-screws m and n. l

The dotted outline R in Fig. 1 shows the position of R after it has beenreleased by the expansion of A. R in Fig. 4: shows its position whenswungto one side for replacement.

'I/Vhen I wish to make use of my invention I place the device upon theupper surface of a vulcanizing-chamber, which is then brought to thedesired temperature and kept there for a short time. The adjusting-screwS is then carefully turned back until it releases the rod R and therebythe alarm D. The rotating stop 15 is then brought up against thethumb-piece h and clamped by the screws 4% and n. The rod R may now bereplaced by swinging it around the point of the adj ustingscrew S, asshown in Fig. i, and if desired the screw S may be turned in a little,when the alarm will not go off until the chamber has reached thecorresponding temperature. The number of degrees corresponding to anyfractional part of a revolution of the screw is 4 readily determined byobservation.

By turning the thumb-piece h back against the rotating stop 25 therelease of the alarm is brought back to its original point.

By the use of the rigid releasing-rod R, held in place by the spring S,I am enabled to adjust the instrument very closely to a giventemperature, and to depend upon its remaining in adjustment thereafter,since the rod R drops clear when released without any tendency to grindoff the point of the adjusting-screw S, while if caught upon the pointof S when A contracts the spring '0 yields and prevents damage.

Having now fully described my invention and the manner of using it, whatI claim, and desire to secure by Letters Patent, is

1. In a thermostat-actuated alarm a compound metallic bar having a flatpart of sufficient length and breadth to serve as a base for the alarmand two ends which bend upward at right angles to the base, incombination with an adjustable connection for the two ends which dropsapart when the two ends are swung out by the unequal expansion of thebar; all as set forth.

2. In a thermostat-actuated alarm, a compound metallic bar which servesas a support for the device and turns upward at the ends, a continuationof one of the strips of the bar upward and inward, a spring-driven alarmattached to this continuation, and means of releasing this alarm by theoutward motion of the ends of the compound bar; all as set forth.

3. In a thermostat-actuated alarm a compound metallic bar whose endsswing outward by expansion; an adjusting-screw passing through one ofthese ends; a T-headed rod passing; through the other end and restingupon the ad jnsting-screw, and a spring pressing the T-head of the rodagainst the outside of the compound bar; all as set forth.

at. In a thermostat-actuated alarm, a sprin gdriven alarm controlled bythe expansion of a compound bar, an adjustin -screw which determines thepoint of release of the alarmdetent, a flat thumb-pieee for turning thisscrew, a rotating" collar bearing a stop for the thumb-piece surroundingthe stem of the adjusting-screw, and one or more screws which hold thecollar in position; all as set forth.

In testimony whereof I have hereunto set my hand this 3d day ofSeptember, A. D. 1805.

FRANK ll. BIGELOXV.

\Vitn esses:

FOREST E. LUDDEN, FANNIE V. SAUNDERS.

